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Full text of "Bulletin of the British Museum (Natural History), Mineralogy"

ROCKS FROM ANTARCTICA: 

THE DISCOVERY COLLECTION 

IN THE BRITISH MUSEUM 

(NATURAL HISTORY) 



D. R. C. KEMPE 



BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
MINERALOGY Vol. 2 No. 7 

LONDON: 1973 



ROCKS FROM ANTARCTICA: 
THE DISCOVERY COLLECTION IN THE 
BRITISH MUSEUM (NATURAL HISTORY) 



BY 

DAVID RONALD CHARLES KEMPE 



Pp. 335-376 ; 7 Plates, 6 Text-figures 



BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
MINERALOGY Vol. 2 No. 7 

LONDON: 1973 



THE BULLETIN OF THE BRITISH MUSEUM 

(natural history), instituted in 1949, is 
issued in five series corresponding to the Departments 
of the Museum, and an Historical series. 

Parts will appear at irregular intervals as they 
become ready. Volumes will contain about three or 
four hundred pages, and will not necessarily be 
completed within one calendar year. 

In 1965 a separate supplementary series of longer 
papers was instituted, numbered serially for each 
Department. 

This paper is Vol. 2, No. y, of the Mineralogical 
series. The abbreviated titles of periodicals cited 
follow those of the World List of Scientific Periodicals. 



World List abbreviation : 
Bull. Br. Mus. nat. Hist. (Miner.). 



Trustees of the British Museum (Natural History), 1973 



TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 

Issued 5 September, 1973 Price £2.45 



ROCKS FROM ANTARCTICA: 
THE DISCOVERY COLLECTION IN THE 
BRITISH MUSEUM (NATURAL HISTORY) 

By D. R. C. KEMPE 



CONTENTS 



I. Introduction 

II. Australian Antarctic Territory 
i Bertha Island, Sheehan Nunatak 
ii Scullin Monolith 
iii Chemistry and discussion 

III. The Scotia Arc 

i Clarence Island . 
ii South Orkney Islands 

(a) Inaccessible Islands 

(b) Coronation Island 

(c) Signy Island 

(d) Powell and Michelsen Islands 

(e) Fredriksen Island 
(/) Laurie Island 
(g) Graptolite Island. 

IV. Basaltic and other rocks from 

DREDGE STATIONS 



i Discovery Tablemount area 
ii Bouvet Island . 
iii Off Dronning Maud Land . 
iv Balleny Islands . 
v Bay of Whales . 
vi Miscellaneous 
vii Chemistry and discussion 
V. Acknowledgements 
VI. References . . . . 



Bouvet Island and various 



Page 
338 
345 
346 
346 
349 
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354 
356 
358 
358 
360 
362 
362 
363 
363 

363 
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368 

369 
369 
369 
371 

373 

374 



SYNOPSIS 

A collection of rocks made by RRS Discovery II and RRS William Scoresby between 1932 
and 1939 from the coast of continental Antarctica, from various islands, and from the bed of 
the Southern Ocean, is described. The petrography of the rocks is presented, with sixteen new 
chemical analyses and three (K/Ar) age determinations. 

Leucocratic, and some basic and ultrabasic granulitic rocks from the coasts of Kemp and 
MacRobertson Lands, Australian Antarctic Territory, are described. The rocks have char- 
nockitic affinities and are characterized also by an abundance of garnet and scarcity of silli- 
manite. A partial analysis of an almandine is reported. The five new chemical analyses of 
the granulites are plotted on FMA and lime-alkalis diagrams and show that the rocks resemble 
the Bunger Oasis (Queen Mary Land) and Madras charnockite series. Age determinations made 



338 ROCKS FROM ANTARCTICA 

on the hornblende and biotite from a basic granulite give 872 and 485 million years (m.y.), 
respectively. These are considered to be the ages of the major granulitization episode and of 
subsequent retrogressive metamorphism. 

Greenschist facies rocks from Clarence Island, in the Scotia Arc, together with igneous and 
other metasedimentary rocks dredged from nearby, are described. The age of a quartz- 
muscovite-graphite schist from Clarence Island is determined as 28 m.y., and suggests a late 
Tertiary extension of the Andean orogeny, known to have affected the Antarctic Peninsula. 
The main Scotia Arc collection, however, comes from the South Orkney Islands. These high 
greenschist facies metasediments include garnet and hornblende schists, and also a group of 
altered microdiorites and andesites, hitherto unreported. Analyses of a schist, a microdiorite 
and two sediments (greywacke and conglomerate) are given ; the latter are from a later sedi- 
mentary sequence present only in the islands at the eastern end of the group. 

The third part of the collection consists of basaltic and other rocks from Bouvet Island and 
several widely separated dredge stations. Two analyses of the Bouvet Island basalts match 
closely the earlier analyses, and are plotted on FMA and lime-alkalis diagrams. Differentiation 
curves are given for Bouvet and for other alkali basalt islands in the South Atlantic ; for 
comparison, curves of the tholeiitic basalt - andesite series of Deception and other South 
Shetland islands are given. An analysed olivine basalt from off the Balleny Islands shows a 
marked resemblance to the olivine basalts and ankaramites from the Tristan da Cunha group 
of islands, and an analysed picritic basalt dredged off Dronning Maud Land has strong affinities 
with the picrite basalt from Gough Island. The tholeiitic ophitic dolerites or coarse basalts 
from this station (one analysis) resemble dolerites from western Dronning Maud Land. Other 
dredged rocks include basic schists (one analysis), adamellitic granites, and greywackes. 



I. INTRODUCTION 

The purpose of this paper is to describe a heterogeneous collection of rocks made by 
RRS Discovery II and RRS William Scoresby between 1932 and 1939 from the coast 
of continental Antarctica, from some of the small islands, and from the bed of the 
Southern Ocean.* Many of these rocks were described some years ago but it would 
seem that an up-to-date account of the entire collection, together with chemical 
analyses and age determinations, would be a useful contribution, in view of the 
current interest in the geophysical, oceanographical and geological problems of this 
region resulting from improved accessibility and the concept of plate tectonics. 

Table I is a catalogue of the rocks in the collection, together with their registered 
numbers and details of their collection. Those from the two continental localities 
were collected by the William Scoresby ; the remainder were collected by the Dis- 
covery II. Most of the collection falls into three main groups ; the remainder comes 
from two or three stations and merits less attention. 

Of the main groups, the first comes from the two localities (Text-fig. 1) in Aus- 
tralian Antarctic Territory : Bertha Island, off Sheehan Nunatak, Kemp Land, 
and Scullin Monolith, MacRobertson Land. 

The second group derives from islands forming part of the Scotia Arc : Clarence 
Osland (PI. 1, 1), in the Elephant Island group, South Shetlands Islands, and the 

* The rocks (144 numbered samples) are deposited in the collection of ocean bottom deposits in the 
Department of Mineralogy, British Museum (Natural History), from which subsamples can be supplied 
for specialist investigations. 



THE DISCOVERY COLLECTION 



339 



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Fig. I. Sketch map of Antarctica and the South Atlantic, to show the localities from 
which specimens were collected. Heavy numbers refer to Discovery Stations, listed in 
'Discovery' Reports 21 and 24, and in Table I. Seamounts are shown as dotted lines 
and the dashed line represents the median rift valley of the Mid-Atlantic Ridge. 



South Orkney Islands (Pis. i, 2 ; 2 ; and 3, 1). The South Orkney rocks were 
collected on two separate cruises, in 1933 and 1937. With these is included a single 
specimen from Tierra del Fuego. 

The third group, dredged off or collected from the Balleny Island group (PL 4), 
near longitude 180 ; and the Discovery Tablemount, Bouvet Island (PI. 3, 2), and 
off Dronning Maud Land, all near longitude o°, are basalts. Included in this 
section are the remaining rocks, dredged from the Bay of Whales and, with the 



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THE DISCOVERY COLLECTION 345 

basalts, near the Discovery Tablemount and off Dronning Maud Land. Many of 
these are probably glacial erratics, including some transported by ice rafting. 

The 'Discovery' Reports by Rayner (1940) and Marr (1935) give full accounts, with 
historical backgrounds, of the William Scoresby's visit to Australian Antarctic 
Territory and the Discovery II's first expedition to the South Orkney Islands. In 
addition, full lists of relevant station numbers, with collection details, are given in 
volumes 21 and 24 of the Reports. Only a brief summary, therefore, of other 
relevant expeditions, both before and after that of the Discovery II, is given here. 

Rock specimens, mainly basalts and other lavas, collected by the first RRS 
Discovery from the southern islands and South Victoria Land during the National 
Antarctic {Discovery) Expedition, 1901-4, are in the rock collections of the British 
Museum (Natural History). They were described by Prior (1907) and catalogued 
by Campbell Smith & Game (1954). The Discovery also dredged in 1927 a 
specimen of andesite from off the Palmer Archipelago, off Graham Land (Campbell 
Smith & Game, 1954, p. 167). 



II. AUSTRALIAN ANTARCTIC TERRITORY 

In 1936, the William Scoresby, whilst marking whales in the Southern Ocean, was 
near the newly explored coasts of Kemp Land and MacRobertson Land. Her 
captain, Lieut Cdr C. R. U. Boothby, R.N.R., took the opportunity of the very open 
ice conditions at that time to make two short 'unofficial' landings. These were 
made by Mr G. W. Rayner on Bertha Island and Scullin Monolith (Text-fig. 1). 

Bertha Island, first thought to be part of the mainland, is 3 miles long, with a 
series of north-south ridges running normal to its length. It is near Sheehan 
Nunatak, in the Sheehan Island group, which forms part of the William Scoresby 
Archipelago, in William Scoresby Bay, between King Edward VIII Gulf and 
Mawson. Scullin Monolith, some 290 km to the east, is a crescent-shaped massif 
rising to 400 m or more, between Mawson and Cape Darnley. 

The British, Australian, and New Zealand Antarctic Research Expedition 
(BANZARE) of 1929-31, under the leadership of Sir Douglas Mawson in the first 
Discovery, visited Scullin Monolith and also Cape Bruce, near Bertha Island. The 
rocks he collected from these localities are described by Tilley (1937). After the 
William Scoresby landings were made (Rayner, 1940), Mr Rayner sent the rocks 
to Tilley who again described them (1940) and compared them with the previous 
collections ; thus two granite gneisses taken from Scullin Monolith by BANZARE 
were compared with about a dozen varied rocks collected by the William Scoresby ; 
and some fifty rocks from Cape Bruce, acquired from two separate landing places 
by BANZARE, were compared with ten specimens from Bertha Island. 

The Australian National Antarctic Research Expedition (ANARE), 1954, visited 
the same region in Kemp Land, but not Cape Bruce or Bertha Island ; it did, 
however, visit Scullin Monolith (Stinear, 1956, unpublished). Neither area was 
visited by the ANARE, 1955-57, but Crohn (1959), describing the results of this 
extended work season, has provided an up-to-date account of the regional geology 
of Australian Antarctic Territory, with notes on the petrology of the main rock types. 



346 ROCKS FROM ANTARCTICA 

i Bertha Island, Sheehan Nunatak 

Of the ten rocks collected by Rayner from this locality, and described by Tilley 
(1940), eight are in the British Museum collection. 

Tilley (1940) refers to the chief rock type of the island as a garnet-hornblende- 
microperthite-quartz gneiss and compares two other specimens, rich in almandine 
garnet, with the gneisses of the Cape Bruce area (Tilley, 1937). These two rocks 
he names as a microperthite-quartz gneiss, with biotite, garnet and accessory 
xenotime ; and a quartz-plagioclase (an desine) -garnet gneiss with spinel enclosures 
in the garnet, both of igneous origin (1940, pp. 181-2). The basic rocks are named 
as hypersthenite and garnetiferous hypersthenite ; mangerite passing into quartz 
norite ; and bands of basic rock described as metamorphosed gabbros or norites. 

Four of the specimens in the collection are leucocratic garnet granulites (PI. 5, 1) ; 
two are basic granulites (metagabbro and metanorite) (Pis. 5, 2 and 3) ; and two are 
metamorphosed ultrabasic rocks {garnetiferous hypersthenites) . Excluding the man- 
gerite-norite category, these groups correspond with Tilley's and represent, re- 
spectively, the country rock ; basic bands within it, varying from a few centimetres 
to a metre or two in width ; and a small outcrop, 5 to 7 m in diameter, towards the 
western end of the island (Tilley, 1940, p. 182, based on field notes provided by 
Rayner). 

The mineralogy of the rocks is given in Table II. In the leucocratic group the 
quartz is often strained and granulated, and the most common ferromagnesian 
mineral is an olive-green hornblende, sometimes derived by alteration of a diopsidic 
augite. Garnet, a partial analysis of which is given in Table III (analysis 1), is 
present in all but the basic granulites. It is a pale pink almandine, typical of 
granulite facies rocks and very similar to the pink almandine from a garnetiferous 
enderbite from Madras (analysis A) (Howie & Subramaniam, 1957). In the basic 
granulites, the plagioclase is andesine-labradorite, accompanied by hornblende, 
often retrogressive after clinopyroxene. Hypersthene occurs in one of the two rocks 
and it is notable that biotite is more abundant in the other. Both the ultrabasic 
rocks are stained green by copper mineralization and the hypersthene-plagioclase 
rock is heavily mineralized with marcasite (ca. 10% by weight). 

ii Scullin Monolith 

The twelve specimens from Scullin Monolith show a greater textural variation. 
Tilley (1940) grouped most of them as quartz-microperthite gneiss, and compared 
some, in which bands of dark smoky quartz are present, with rocks from the Cape 
Bruce area (Tilley, 1937). These twelve specimens include three leucocratic garnet 
granulites (PI. 5, 4) and six garnet gneisses, of which two are granulitic and one 
granitic ; two garnetiferous quartzites (quartz veins) ; and a single garnetiferous 
basic granulite (the hornblende norite of Tilley, 1940, p. 181). 

In the leucocratic rocks, the quartz is again usually strained and granulated, 
especially in the quartzites, and in some (e.g. 130 (2)) it occurs, as noted by Tilley, 
as bands of the dark smoky variety. The alkali feldspar is bleb or hair microper- 
thite and in two specimens (130 (1) and (8)) forms large ' phenocrysts ' or porphyro- 
blasts reaching 2-5 cm in length. One leucocratic garnet granulite (130 (1)) contains 



THE DISCOVERY COLLECTION 



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348 



ROCKS FROM ANTARCTICA 





Ti 


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WITH A 


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0-008 


Fe 3 + 


- 






0-240 


Fe 2 + 


3-82o < 






3-670 


Mn 


- 






0-084 


Mg 
Ca 


1-763 
0-450 


>6-03 




1-826 
o-374 


Na 


- 






0-036 


K 


- 






0-002 


Almandine 


64 




6l*2 


Andradite 


- 




6-2 


Grossularite 


7 




0-7 


Pyrope 


29 




30-5 


Spessartine 


- 






i-4 



■ 6-oo 



-4-04 



5-99 



Almandine garnet, leucocratic garnet granulite, Bertha Island, BM 1972, O, 129 (6). (Analyst: 
R. F. Symes.) (Partial analysis by electron microprobe; calculation ignores andradite and 
spessartine components.) 

Pink almandine garnet, garnetiferous enderbite (Ch 113) (charnockite series), Pallavaram, Madras, 
India (Howie & Subramaniam, 1957). (Analyst: R. A. Howie.) 



white patches of feldspar with green irregular intergrown cores of quartz. The 
rocks, on the whole, contain lesser amounts of ferromagnesian minerals than their 
nearest equivalents from Bertha Island. Hornblende is virtually absent and a 
little clinopyroxene is found in onby one specimen ; there is no hypersthene. Biotite 
is present in all except the quartzites, and garnet is found in every rock ; both these 
minerals are sparsely distributed (Table II) and the garnet is sieved with inclusions 
of quartz and biotite. Sphene does not occur amongst the accessory minerals, 
whilst apatite, in one rock, forms large widely disseminated oval blebs and localized 
crystal aggregates. Green spinel (near gahnite) is present in one granulite and the 
thin section of a quartzite contains a single cross-section of sillimanite. 



THE DISCOVERY COLLECTION 



349 



Thus, the two groups of granulites, containing hypersthene in only four out of 
twenty rocks, are notable in that they lack garnet only in the two basic granulites 
from Bertha Island, this mineral being present in the single similar rock from 
Scullin Monolith. The scarcity of sillimanite in a suite of granulites is surprising 
and the apatite blebs are unusual. 



iii Chemistry and discussion 

In Table IV (analyses I to 4), chemical analyses, with their CIPW norms, are given 
of a leucocratic granulite and a basic granulite each from Bertha Island and Scullin 
Monolith. An analysis of the mineralized garnetiferous hypersthenite from Bertha 
Island, recalculated on a sulphide-free basis, is also presented (analysis 5) ; its rela- 
tively high Si0 2 content results from the presence of plagioclase. Three analyses 
are also presented in Table IV for comparison. Of these, the first is of a garnet 
granulite from Proclamation Island, Enderby Land, some 290 km west of Bertha 
Island (Tilley, 1937, p. 10). In Si0 2 content it lies between the two similar Discovery 
rocks but differs somewhat in its content of other oxides. This is not surprising 
since in rocks of this (granitic) composition slight variations in the modal content 
of the ferromagnesian minerals will result in proportionally large variations in certain 
elements. 



Table IV 

Analyses, some Trace Elements, and CIPW Norms of Granulites 
from Australian Antarctic Territory 







Leucocratic rocks 




Basic and ultrabasic rocks 




1 


A 


2 


B 


3 


4 


5 


C 


Si0 2 


81-02 


73-84 


68-43 


62-31 


50-35 


46-50 


5060 


51-79 


Ti0 2 


o-37 


009 


o-93 


138 


o-6o 


2-43 


0-87 


1-16 


Al 2 O s 


9-27 


1406 


12-84 


14-10 


15-63 


15-49 


7-72 


15-62 


Fe 2 3 


0-51 


tr 


i-6i 


1-92 


1-25 


1-27 


3-I5 


i-93 


FeO 


0-98 


i-55 


4-36 


663 


690 


12-28 


19-60 


8-42 


MnO 


o-oi 


nil 


O-II 


0-20 


016 


0-23 


0-30 


0-25 


MgO 


0-38 


0-41 


1-22 


1-71 


8-6i 


7-68 


13-45 


7-00 


CaO 


1-14 


1-65 


2-92 


4-80 


990 


9-42 


2-26 


9-79 


Na 2 


i-6i 


2-72 


2-00 


2-72 


3-4° 


261 


1-50 


2-29 


K 2 


4-07 


5-08 


5 -i8 


372 


1 96 


1-22 


0-28 


0-87 


H 2 0+ 


o-59 


0-25 


o-37 


- 


0-87 


o-59 


0-41 


- 


H 2 0- 


o-io 


0-25 


0-05 


- 


0-12 


006 


nil 


- 


P 2 O s 


0-09 


nil 


0-26 


0-36 


OO6 


0-30 


- 


0-16 


S 


0-02 


- 


0-04 


- 


0-08 


013 


- 


- 


co 2 


O79 


nil 


o-35 


- 


0-58 


0-32 


0-27 


- 


Others 


- 


- 


- 


o-33 


- 


- 


- 


1-27 


Less 0=S 


OOI 


- 


0-02 


- 


0-04 


0-06 


- 


- 


Total 


IOO-94 


99-90 


IOO-65 


100-18 


IOO-43 


100-47 


100-41 


100-55 
















[Continued overleaf 



350 ROCKS FROM ANTARCTICA 

Table IV (cont.) 

Trace elements (p. p.m.) 



Cr 






20 




120 




nil 


100 


400 




Li 






19 




9 




23 


37 


20* 




Ni 






nil 




15 




50 


100 


2100 




Cu 






10 




5 




5 


15 


20* 




Zn 






280 




230 




280 


400 


780* 




V 






25 




40 




250 


400 


300 




Zr 






500 




2000 




70 


400 


50 




Y 






nil 




170 




nil 


80 


nil 




Sr 






100 




250 




200 


325 


tr 




Ba 






400 




500 




100 


400 


50 




Rb 






73 




9i 


Norms 


9i 


137 


160* 




q 






52-96 


33-20 


27-63 


17-81 


- 


- 


1-84 


2-36 


c 






0-36 


1 -09 


- 


- 


- 


- 


1-47 


- 


or 






24-06 


30-03 


30-62 


21-99 


"•59 


7-21 


1-66 


5-14 


ab 






13-62 


23-01 


16-92 


23-01 


20-20 


20-84 


12-69 


19-38 


an 






5-07 


8-19 


10-76 


15-28 


21-61 


26-95 


9-5i 


29-78 


ne 






- 


- 


- 


- 


4-64 


o-68 


- 


- 


di 






- 


- 


1-71 


5-24 


21-99 


14-72 


- 


I4-52 


hy 






i-73 


3-72 


7-52 


10-28 


- 


- 


66-01 


22-74 


ol 






- 


- 


- 


- 


15-63 


21-89 


- 


- 


mt 






o-74 


- 


2-33 


2-78 


i-8i 


1-84 


4-57 


2-80 


il 






0-70 


0-17 


1-77 


2-62 


1-14 


4-62 


1-65 


2-20 


ap 






0-21 


- 


o-6i 


0-85 


0-14 


0-71 


- 


0- 3 8 


ct 






- 


- 


- 


- 


- 


- 


o-6i 


- 


i 


Leucocratic garnet granulite, 


Scullin 


Monolith, 


BM 1972, O, 130 


(3). (Analysts: C. 


J. Elliott, 




V. 


K. 


Din and A. 


J. Easton.) 














A 


Garnet granulite, 


Proclamation Island 


Enderby 


Land (no. 154) (Tilley, 1937, 


p. 10). 


(Analyst : 



C. E. Tilley.) 

2 Leucocratic garnet granulite, Bertha Island, BM 1972, O, 129 (1). (Analysts: C. J. Elliott, V. K. 
Din and A. J. Easton.) 

B Charnockite (granosyenite), Charnokitovyy Island, Bunger Oasis (no. 367) (Ravich & Kuno, 
1961, p. 66). 

3 Basic (diopside) granulite, Bertha Island, BM 1972, O, 129 (2). (Analysts: C. J. Elliott, V. K. 
Din and A. J. Easton.) 

4 Basic (hypersthene) granulite, Scullin Monolith, BM 1972, O, 130 (10). (Analysts: C. J. Elliott, 
V. K. Din and A. J. Easton.) 

5 Garnetiferous plagioclase hypersthenite, Bertha Island, BM 1972, O, 129 (8). (Analysts: C. J 
Elliott, V. K. Din and A. J. Easton; analysis carried out on sulphide-free fraction; * : determined 
on total rock.) 

C Charnockite (quartzy gabbro-norite), Smelykh Island, Bunger Oasis (no. 446) (Ravich & Kuno, 
1961, p. 66). 

The second and third analyses are of two charnockites from Bunger Oasis, Eastern 
Antarctica (Ravich & Kuno, 1961). The first (B) resembles the garnet granulite 
from Bertha Island, the second (C) the more basic Discovery rocks ; in each case 
there are differences in the content of various elements. For example, the basic 
granulite from Bertha Island is somewhat deficient in iron. Both the basic granu- 
lites from Australian Antarctic Territory contain normative nepheline. 

The trace elements, which in most cases are present in similar quantities to those 
in the Madras charnockite series (Howie, 1955), show limited patterns of change from 



THE DISCOVERY COLLECTION 35I 

the leucocratic to the basic granulites. There are increases in Li (substituting for 
Mg), Ni and V, whilst Zr shows a decrease. In the remaining elements determined 
(Cr, Cu, Zn, Y, Sr, Ba and Rb), little systematic change can be seen. There is a 
large increase in zinc in the hypersthenite but this is attributable to the sulphide 
mineralization. 

Charnockites described by Nockolds (1940) from Eastern Queen Mary Land, 
and to a lesser extent those from Western Queen Mary Land and Kaiser Wilhelm II 
Land (see Text-fig. 1), also resemble the Discovery rocks in many respects. This 
applies particularly to the ferromagnesian mineral content. Garnet, so well repre- 
sented in the rocks described in the present account is, however, absent from the 
Queen Mary Land rocks except for the acid igneous gneisses. 

If analyses 1 to 5 of Table IV are plotted on triangular diagrams using the 
parameters total FeO-MgO-(Na 2 + K 2 0) and CaO-Na 2 0-K 2 0, respectively, as 
chosen by Howie (1955) to illustrate the trends within the Madras charnockite 
series, they fall fairly close to the curves given by Howie (Text-figs. 2 and 3) or even 
closer to the curves (or their extensions) obtained for the Bunger Oasis rocks. It is 
interesting to note that the Bunger FMA curve forms a continuation of the more 
magnesian curve of Howie. Howie (1955) considered that the regularity of the plots 
of the Madras rocks suggested that they belong to a single series of plutonic igneous 
rocks and this argument can also be applied to the Bunger Oasis series. The very 
small number of points for the Discovery rocks, and their compositional range, 
precludes any such generalization in their case but there is no evidence to suggest 
that they represent, say, a random group of metamorphosed sediments ; moreover, 
Tilley (1940) regarded all the Scullin and most, if not all, of the Bertha Island rocks 
as igneous in origin. There is no doubt of the igneous origin of the basic and ultra- 
basic rocks but it is less easy to be certain of the origin of some of the leucocratic rocks. 

In view of the absence of hypersthene in sixteen out of twenty of the Antarctic 
rocks, and in order to respect Holland's (1900) definition of the term, these rocks 
should not be named charnockites. Nevertheless, they are undoubtedly typical 
examples of rocks of the granulite facies of metamorphism, closely resembling rocks 
from, for example, Madras (Holland, 1900 ; Howie, 1955 ; Subramaniam, 1959) ; 
East Africa (e.g. Groves, 1935) ; Lapland (Eskola, 1952) ; and other parts of 
Antarctica (Tilley, 1937 ; Stinear, 1956, unpublished ; Crohn, 1959 ; McLeod, 1964 ; 
Klimov, Ravich & Soloviev, 1964 ; McCarthy & Trail, 1964). Retrogressive meta- 
morphism is evident in the change from clinopyroxene to hornblende (and biotite) 
but the majority of the rocks were probably originally to be placed in the pyroxene 
(charnockitic) subfacies. 

The (K/Ar) age of the basic granulite from Bertha Island (Table IV, analysis 3) 
has been determined by C. Rundle on the biotite and hornblende. The biotite 
gives an age of 485 ± 9 m.y., whilst the hornblende gives 872 + 21 m.y. (average 
of two determinations). These compare with ages of 750-650 m.y. for the char- 
nockitisation of the Bunger Oasis rocks (Ravich & Kuno, 1962, p. 67) and of 650- 
490 m.y. for the charnockites and their xenoliths of the Mawson area (Ravich & 
Krylov, 1964, p. 582). These ages suggest an intermittent major orogenic and meta- 
morphic event, spread over an immense period of time. Most of the ages listed by 



352 



ROCKS FROM ANTARCTICA 
(total) FeO 



Na 2 OK 2 




ol X 



K2O 



>MgQ 



Na 2 




CaO 



THE DISCOVERY COLLECTION 353 

Ravich and Krylov (1964) were determined on whole rocks, determinations on which 
almost invariably yield younger ages than those given by individual minerals (p. 579). 
Probably the older (hornblende) age on the Bertha Island granulite gives a fair 
estimate of the age of much of the original granulite facies metamorphism, whilst 
that of the biotite relates to the retrogressive phase some 400 m.y. later. The 
general ages of the later stages of metamorphism compare fairly closely with the last 
regional metamorphic ages of similar rocks from Madras - 500 m.y. (Aswathanaray- 
ana, 1964) and 550-600 m.y. (Sarkar et al., 1964, p. 536) - and the East African region. 



III. THE SCOTIA ARC 

In 1932 Discovery II visited Mount Boucheron, Shoal Bay, in the Cockburn 
Channel, Tierra del Fuego (Text-fig. 1) ; a single specimen of quartz-mica schist 
was collected and is included in the British Museum collection. 

In 1936 she called at Clarence Island, in the Elephant Island group, South 
Shetlands (Text-fig. 1), where a collection of nine rocks was made. On the same 
occasion, rocks were dredged off Cape Bowles (on the southern side of the island) ; 
3 months later, early in 1937, further dredging took place to the south-east of the 
island. Prior to this, in 1928, Professor Holtedahl landed briefly on the island 
and made the first collection (see Holtedahl, 1929, and Barth & Holmsen, 1939), 
whilst limited collections were made from Elephant Island (by Mr G. V. Douglas 
in the Quest, 1922) and from Gibbs and Narrow Islands (by Mr J. W. Marr in the 
Discovery II, February (sic) 1937 ; these rocks are not in the British Museum 
collection). Recently, the Joint Services Expedition to Elephant Island, 1970-71, 
made a thorough collection from that island and limited collections from the remainder 
of the group (Roxburgh & Burkitt in Burley, 1971, pp. B1-2). This collection has 
been deposited with Dr R. J. Adie, of the British Antarctic Survey, at the University 
of Birmingham. 

Rocks dredged from near Clarence Island were described by Tyrrell (1945) and 
are presumably those collected by Discovery II in 1937. This material, together 
with many other specimens collected by Discovery II in 1934 and 1937 from West 
Antarctica and the Scotia Arc, which are housed elsewhere, were submitted to 
Professor Tyrrell for description. He does not appear to have received the shore 
collection from Clarence Island made in 1936, reference to which is omitted from 
Roxburgh & Burkitt's (1971, p. Bi) account of previous landings on the Elephant 
Island group. Rocks from Elephant Island collected by Douglas during the 
Shackleton-Rowett Expedition in the Quest were described by Tilley (1930) and a 
full bibliography of other early works on the geology of the Scotia Arc is given by 
Tyrrell (1945) or in papers listed therein. 

Figs. 2 and 3. Triangular diagrams (molecular percentages) for analysed granulites from 
Australian Antarctic Territory. 2 : (total) FeO-MgO-(Na 2 + K 2 0). 3 : CaO-Na 2 0- 
K 2 0. Solid lines, curves for the Madras charnockite series from Howie (1955) ; dashed 
lines, curves plotted from analyses of the Bunger Oasis charnockites given by Ravich 
& Kuno (1961). Numbers (solid circles) and letters (open circles) refer to analyses of 
rocks from A.A.T. and Bunger Oasis given in Table IV. 

6* 



354 ROCKS FROM ANTARCTICA 

The earliest collection from the South Orkney Islands was made in 1838 by members 
of d'Urville's expedition (d'Urville, 1842, pp. 70 and 316-17). The Scottish National 
Antarctic Expedition spent the winter of 1903-4 on Laurie Island (cf. Pirie, 1905 
and 1913) ; and Signy Island was visited by Holtedahl in 1928 (Holtedahl, 1929 ; 
Barth & Holmsen, 1939). 

Separate major collections of rocks from the South Orkney Islands were made by 
Discovery II in 1933 and 1937. The earlier collection only is described by Tilley 
( I 935) J possibly it was considered that no further comment was needed on the 
second collection (Wordie in Tyrrell, 1945, p. 40). Nine mainly metamorphic rock 
specimens from the South Orkney Islands, collected in 1915 by A. G. Bennett and 
similar to many collected by Discovery II, are in the rock collections of the British 
Museum (Natural History) (Campbell Smith & Game, 1954, p. 166).* 

More recently, the geology of some of the South Orkney Islands has been system- 
atically described by members of the British Antarctic Survey. The geology of 
Signy Island, on which is maintained a field station, is well known (Matthews & 
Maling, 1967 ; Thompson, 1968), and the petrography of the metamorphic rocks 
from the Inaccessible and Larsen Islands has been described by West (1968). Con- 
siderable further work is in progress. 



i Clarence Island 

The shore collection made from Clarence Island (PL 1, 1) in 1936 by Dr F. D. 
Ommanney consists of nine low-grade (greenschist facies) metasediments. They 
were collected from the scree slope on an exposed cliff rising sheer about 245 m 
above the landing place (detail from the Biological Log) ; the bedding was marked, 
dipping some 15° to the east. The phyllites are quartz-rich and more than half are 
graphitic : clearly they derive from impure carbonaceous sandstones (? greywackes). 

Of the nine rocks, collected at various levels between 10 and 150 m above sea 
level, three were selected for sectioning as being typical of the group ; petrographic 
descriptions are given below. 

BM 1972, O, 133 (2) Quartz-muscovite-graphite schist (Station 1874). A corrugated phyllitic 
rock, containing some epidote, and a little brown and green tourmaline and sphene. The rock 
is veined by quartz, running parallel to the schistosity. From about 30 m above sea level. 
1972, O, 133 (4) Quartz-mica-graphite schist (PI. 6, 1). A highly corrugated phyllite, in which 
muscovite, biotite and chlorite are present, with some epidote, sphene and iron ore, including 
hematite. From about 30 m above sea level. 

1972, O, 133 (8) Quartz-epidote-muscovite-chlorite schist. A compact, slightly schistose, fine- 
grained rock, with micro-corrugations ; it is cut by a mosaic of fine quartz veins. The main 
minerals are accompanied by some potassium feldspar and a little sphene. From 1 to 150 m 
above sea level. 

These rocks strongly resemble some of the metamorphic types described by 
Tyrrell (1945) from the dredged (1937) collection ; one such example is illustrated 
by him (p. 82, fig. 11). 

* Sandstone from Powell Island [BM 1920, 139]; garnet-hornblende schist, garnetiferous schists, 
epidote-hornblende schist, and crystalline limestone, from the north end of Signy Island [BM 1920, 276; 
1921, 700]. 



THE DISCOVERY COLLECTION 



355 



Two sets of dredged rocks and pebbles are in the British Museum, collected, as 
mentioned above, in 1936 and 1937. The earlier group (Station 1873) consists of 
several hundred pebbles, ranging from less than 2 to 20 cm in diameter, of meta- 
morphic rocks : phyllites, chlorite schists, marbles and (metacalcareous) epidosites. 
Two were sectioned for closer examination. 

The second batch from Station 1957 comprises two specimens of granite and many 
very small granitic and low-grade metamorphic pebbles. Many of these may be 
glacial erratics. One of the larger specimens, a granodiorite, was sectioned. 

1972, O, 132 (1) Epidosite (Station 1873). A metamorphosed calcareous sandstone now com- 
prising epidote and quartz, with lesser chlorite and some iron ore. 

1972, O, 132 (2) Epidosite. A banded, somewhat schistose rock, in which layers of fine-grained 
epidote and quartz alternate with coarser layers of quartz with biotite, chlorite and calcite. 
1972, O, 134 (1) Granodiorite (Station 1957). A typical oligoclase-quartz rock, with slight 
alteration resulting in sericitization of the feldspar. The ferromagnesian mineral is biotite, 
largely chloritized, and there is some epidote and sphene. The quartz shows local granulation 
resulting from shear stress. 

The porphyries or microgranites and rhyolite described by Tyrrell (1945) are not 
present : nor are the unmetamorphosed greywackes or amphibole-bearing meta- 
morphic rocks. The latter - quartz-epidote-amphibole schists - are apparently 
similar to those collected by Holtedahl in 1928 and described by him (1929) and by 
Barth & Holmsen (1939) ; they were considered by Tyrrell to be derived from basic 
igneous rocks or their tuffs. Two analyses of these greenschists are given by Barth 
& Holmsen and are reproduced here (Table V). 

Table V 
Analyses and CIPW Norms of Greenschists from Clarence Island 



Si0 2 


57-66 


47-37 


TiO a 


0-85 


I-20 


A1 2 3 


16-30 


16-46 


Fe s O, 


3-46 


I-92 


FeO 


2-46 


7- 4 I 


MnO 


O-II 


0-15 


MgO 


3-95 


8-64 


CaO 


6-oi 


10-19 


Na 2 


4-39 


2-74 


K 2 


2-68 


0-06 


H 2 0+ 


0-98 


3-38 


H a O- 


010 


o-io 


p 2 o 5 


o-55 


0-14 


S 


0-19 


0-02 


co 2 


012 


0-21 


CI 


0-02 


nil 


BaO 


0-08 


- 


Less 0=S, CI 


o-io 


o-oi 


Total 


99-81 


99-98 



[Continued overleaf 



356 ROCKS FROM ANTARCTICA 





Table V (cont.) 






Norms 




q 


6-6 3 


- 


or 


15-84 


0-36 


ab 


37-14 


23-18 


an 


16-86 


32-44 


di 


6-73 


12-84 


hy 


7-16 


n-8i 


ol 


- 


IO-OI 


mt 


5-02 


2-78 


il 


i-6i 


2-28 


ap 


1-30 


o-33 


ct 


0-27 


0-48 



A Biotite-epidote-actinolite schist (no. 22) (not very schistose). (Analyst: E. Kliiver.) 
B Chlorite-actinolite-clinozoisite-albite schist (no. 23) (very schistose). (Analyst: E. Kliiver.) 
(From Barth and Holmsen, 1939, p. 60.) 

Tyrrell summarizes the geology of the Elephant and Clarence Island group, 
together with that of the South Orkneys, as a typical geosynclinal greenstone- 
greywacke-mudstone association (1945, p. 88). 

The age of the quartz-muscovite-graphite schist (1972, O, 133 (2)) has been deter- 
mined (K/Ar) by C. Rundle at 28 ± 3 m.y. This is very young in comparison with, 
for example, the South Orkney Islands quartz-mica schists (ca. 187 m.y.), discussed 
on p. 360. Angino & Turner (1964) quote examples of Cenozoic (Tertiary) meta- 
morphic and orogenic activity, ranging from 100 down to 6 m.y. (pp. 554-5). The 
most likely explanation for the Clarence Island age is that it represents a late Ter- 
tiary extension of the Andean orogeny (75-110 m.y.), which is known to have 
affected the Antarctic Peninsula. 

ii South Orkney Islands 

The South Orkney Islands (Text-fig. 4) were visited by the Discovery II in 1933 
and 1937, and shore collections were made by Mr J. W. S. Marr. In 1933 the ship 
visited Inaccessible, Coronation, Signy, Powell and Michelsen, Fredriksen and 
Laurie Islands ; in 1937 Inaccessible, Powell and Michelsen, and Fredriksen Islands 
were not visited, but a few rocks were dredged from a station to the south of Corona- 
tion Island, and landing was made on Graptolite Island. 

The earlier collection of rocks was described by Tilley (1935), so that the greatest 
interest lies in the hitherto undescribed 1937 collection. The rocks correspond well 
with the general geology of the South Orkney Islands (Tilley, 1935 ; Matthews & 
Maling, 1967 ; Thompson, 1968). This is shown in Table VI (and see p. 360) and 
Text-fig. 4 : a metasedimentary Basement Complex to the west, possibly rising in 
grade to the south and west, with a greywacke-shale series, surmounted unconform- 
ably by a younger conglomerate, to the east. 

Correlation with Clarence Island and others in that group is not possible on present 
evidence, but similarities in the geology of the Elephant Island group and the 
South Orkneys have been noted by Tyrrell (1945), Matthews & Maling (1967), 
Thompson (1968), West (1968) and Harrington et at, (1972). 



THE DISCOVERY COLLECTION 



357 










ON " 




(^ 1- 
S 13 

Ih 

.a s § 

.2 g "^ 

O 5 5P 

w p <u 

^ C <" 

>> « 

. > a) 



358 



ROCKS FROM ANTARCTICA 



Table VI 
Stratigraphical Succession in the South Orkney Islands 



Age 



? Cretaceous 



? Jurassic 



Group 

Spence Harbour 
Conglomerate 

Powell Island 
Conglomerate 

Laurie Island 
Conglomerate 

Derived Series 



? Carboniferous Greywacke-Shale 

Series 



Generalized 
trend of folds 

E-W (insig- 
nificant) 

E-W 

Not known 

Not known 
NNW-SSE 



Outcrop areas 

East end of Coronation 
Island 



Powell Island 
Laurie Island (?) 



Known only as boul- 
ders in conglomerate 

Powell and Laurie 
Islands 



? Precambrian 



Post- Basement 
Complex 



Basement Complex 
(metasediments) 

Dolerites (not 
metamorphosed) 



N-S 



Dykes trend 
WNW-ESE 



Coronation and Signy 
Islands 

Intrude Basement 
Complex 



(From Matthews & Maling, 1967, p. 2.) 

(a) Inaccessible Islands : Station 1094 

Several samples of a single rock (field no. 61) - hornblende-epidote schist - are 
in the 1933 collection. This is probably the rock described by Tilley (1935) as 
chlorite-epidote schist, although West (1968, p. 45) states that the commonest type 
contains hornblende and only a little (retrograde) chlorite. Note No. 256 (from the 
Biological Log) states that this dark-green, fine-grained rock, with some quartz 
veins, forms the main rock type of the islands. 

1972, O, 135 Hornblende-epidote schist. A compact, fine-grained rock consisting of bluish- 
green hornblende, epidote, albite and quartz, with accessory rutile, altering to, and often 
mantled by, sphene. Apatite and iron ore are also present. 



(b) Coronation Island : Stations 1091, 1963 and 1964 

According to Note No. 253 and the Biological Log, thirteen single or multiple 
samples were collected from or around Sandefjord Bay (Pis. 1, 2 and 2, 1) in 1933, 
and a further three in 1937. Also, on the second visit, three more specimens were 
collected from the north-west corner of the island (Station 1964). Most of the speci- 
mens accorded to Station 1091, however, were collected from Governor [Guvernen] 
Island(s), also off the north-west corner of the main island and those of Station 1963 
from Larsen Island. 



THE DISCOVERY COLLECTION 359 

Grey, graphitic phyllitic schists, occasionally garnet-bearing, and epiclote-chlorite 
schists (of the greenschist facies) form the most common rocks, plentifully cut by 
quartz veins reaching 10 m in breadth. The rocks are quartz-rich and probably 
represent metamorphosed greywackes ; there are some marble bands interbedded 
with the schists. 

Mica schists were collected at heights ranging from sea level up to about 30 m 
from Governor Island, from small islands in the strait north of Governor Island, 
and from the base of the mountain overlooking Sandefjord Bay, on Coronation 
Island. Observations on the dip and strike of the rocks are too variable to be of 
value but Matthews and Maling (1967) record that the generalized trend of the folds 
within the Basement Complex is north-south. 

The Discovery II also called at Useless Bay, on the south coast of Coronation 
Island (Station 1093). Rocks from this locality are absent from the British Museum 
collection (as are many from Station 1092) ; according to Note No. 255 they are 
similar to those from Signy Island. 

1972, O, 136 (8) Biotite schist. A fine-grained rock comprising quartz, biotite and graphite, 
with some epidote, chlorite and muscovite, and accessory apatite, allanite and iron ore. 
1972, O, 136 (13) Quartz-muscovite-chlorite schist. A layered rock in which quartzitic layers 
alternate with bands rich in muscovite, chlorite, quartz and epidote. Perthite and potassium 
feldspar, and a little allanite, apatite and iron ore are present, as are occasional lenses of calcite. 
1972, O, 138 (3) Garnet-mica schist. A layered rock, typical of a phyllitic schist derived from a 
mixed arenaceous sedimentary sequence. Quartz, with muscovite, brown biotite and chlorite, 
form the main constituents, with some epidote in boat-shaped grains. Locally, layers rich in 
calcite, with quartz and muscovite, occur, and there are small amounts of sphene, potassium 
feldspar, graphite and iron ore. Sparse garnets are found, 'rolled' in envelopes of chlorite. 

The three specimens from Larsen Island (Station 1963) are notable in that, unlike 
most of the others, they are altered igneous rocks. They consist of a greenish 
altered quartz microdiorite 'from the outcrop immediately above that of the fine- 
grained green rock [altered andesite] in the general gneissose mass at the south- 
western corner of Larsen Island'. It is probable that they represent a volcanic 
interpolation within the metasediments, the microdiorite being a coarse-grained 
variant of the main mass. An analysis of the microdiorite is given in Table VII. 

1972, O, 137 (1) Altered quartz microdiorite (PI. 6, 2). The rock mainly consists of saussuritized 
plagioclase and greenish-yellow chlorite after pyroxene and hornblende, of each of which a few 
crystals remain. There are interstitial grains of quartz, iron ore, some yellow epidote, calcite, 
long acicular needles of apatite and a little myrmekite. 

1972, O, 137 (2) Altered porphyritic quartz andesite. Mainly saussuritized plagioclase forming 
both phenocrysts and groundmass laths, with patchy yellow epidote and chlorite. Iron ore, 
calcite and a few quartz crystals make up the rock. 

Tilley (1935, p. 386) described from Larsen Island grey phyllitic rocks, similar 
to those from Coronation Island, but examples of these also are not represented in 
the British Museum collection. 

No igneous rocks resembling those described above are recorded from the Larsen 
Islands by West (1968), with the possible exception of the grey-green altered doleritic 
dyke rock from the north-east coast of the southernmost of the Larsen Islands. 



3 6o ROCKS FROM ANTARCTICA 

(c) Signy Island : Stations 1092 and 1962 

The Discovery II collected more rocks from this, the best known geologically, 
than from any other island (nineteen in 1933, two in 1937) ; in 1933, according to 
Note No. 254, they were recorded as crystalline limestone and, chiefly, gneissose 
rocks such as garnet-bearing dark-green mica schists. Tilley (1935) grouped the 
Signy Island rocks into marbles ; garnet-hornblende schists ; garnet-hornblende- 
biotite schist ; and garnet-mica schists. 

Miller (i960) and Rex (1967, unpublished) have determined the ages (K/Ar, on 
biotite) of the (? latest) metamorphism affecting the quartz-mica schists of Corona- 
tion, Signy and Moe Islands. They obtained ages varying between 176 and 199 m.y. 
(Lower Jurassic to Upper Trassic), but Rex's mean age (183 m.y.) corroborates 
Miller's (187 m.y.). 

Matthews & Maling (1967, p. 8) give a detailed succession for the south-west part 
of the island, of which the rock types are discussed in detail by Thompson (1968). 
The outline succession comprises : 

Moe Island Series (quartz-mica schists) 
Amphibolite Series (includes some garnetiferous types) 
Marble Series (upper part : highly variable) 
Marble Series (lower part) 

Below are brief petrographic descriptions of representative rocks in the British 
Museum collection. With the exception of quartz-mica schists, which are similar 
to the garnet-mica schists, they include the most common types and suggest that 
a metamorphic grade approaching the amphibolite facies (the highest in the South 
Orkney group) is reached at this locality. The rocks of Borge Bay are notable for 
the size of their garnets (up to 2-5 cm in diameter) and were distinguished by Tilley 
(1935, p. 388) because of their richness in biotite. However, it would seem that this 
is not invariably the case and that Tilley's garnet-hornblende schists and garnet- 
hornblende-biotite schist are merely variants of the same rock type. 

An analysis of the actinolite-chlorite-epidote schist, 1972, O, 139 (8), is given in 
Table VII. The rock is a typical greenschist, probably derived from a basaltic 
igneous rock, and similar to those from Clarence Island (Table V) and, to a lesser 
extent, the chlorite-hornblende schist amongst the rocks dredged off Dronning Maud 
Land (pp. 368, 373 and Table IX). 

The chlorite from this rock has been examined by X-ray diffraction using part of 
the technique of Brindley & Gillery (1956). Accurate measurement of the 
d ooi spacing gives 14-160 A, from which can be estimated the amount of A1 IV 
replacing Si in the structure. This determination was made in order to compare 
this chlorite with other chlorites from a chlorite-mica schist from Laurie Island, 
1972, O, 144 (10), and with a chlorite in the chlorite-hornblende schist from off 
Dronning Maud Land (Table IX, analysis 3), mentioned above. The Laurie Island 
chlorite, with d ooi of 14-156 A, is not significantly different, whilst that from off 
Dronning Maud Land, with d ooi of 14-204 A, can be regarded as different in 
having less A1 IV in the structure. This mineral is seen in thin section to differ 



THE DISCOVERY COLLECTION 



361 



Table VII 

Analyses, some Trace Elements and CIPW Norms of Rocks from 

the South Orkney Islands 





1 


2 




Norms 




3 


A 


4 


B 


Si0 2 


55-i8 


47-47 










64-68 


64-7 


78-52 


76-84 


TiO a 


152 


2-03 




1 


2 


• 


0-74 


o-5 


0-46 


- 


A1 2 3 


15-09 


16-79 


q 


8- 4 8 


6 


54 


15-89 


14-8 


io-43 


11-76 


Fe 2 O s 


3-05 


3-15 


or 


3-84 


3 


■61 


0-36 


i-5 


015 


o-55 


FeO 


6-90 


5-85 


ab 


37-47 


9 


14 


3-94 


39 


2-88 


2-88 


MnO 


0-17 


0-18 


an 


19-32 


39 


17 


0-07 


o-i 


005 


tr 


MgO 


3-60 


7-84 


di 


4-3° 


5 


08 


2-60 


2-2 


I-I3 


i-39 


CaO 


5-92 


10-64 


hy 


14-81 


22' 


23 


1-36 


3-i 


116 


0-70 


Na 2 


4H3 


1-08 


mt 


4-43 


4-57 


335 


3-i 


2-90 


2-57 


K 2 


0-65 


o-6i 


il 


2-89 


3' 


86 


3-06 


1-9 


i-55 


1-62 


H 2 0+ 


278 


2-71 


ap 


°-57 


O' 


54 


2-24 


2-4 


1-41 


1-87 


H 2 0- 


0-09 


0-02 


ct 


123 


2' 


07 


010 


0-7 


o-oi 


- 


P a O s 


0-24 


0-23 










016 


0-2 


0-15 


- 


s 


- 


0-05 










0-07 


o-6 


0-07 


- 


co 2 


o-54 


0-91 










0-76 


i-3 


o-34 


- 


Less O s 


= S 


0-02 










003 


o-3 


0-03 


- 


Total 


IOO-lT) 


99-54 










99-35 


100-7 


101-18 


100-18 










Trace elements (p.p. 


m.) 








Cr 




500 










60 




15 




Ni 




120 










50 




< 5 




V 




200 










100 




75 




Zr 




150 










400 




400 




Y 




25 










50 




20 




Sr 




750 










430 




200 




Ba 




200 










650 




400 




Rb 




9 










55 




14 





A 
4 

B 



Altered quartz microdiorite, Larsen Island, BM 1972, O, 137 (1). (Analyst : V. K. Din.) 

Actinolite-chlorite-epidote schist, Borge Bay, Signy Island, BM 1972, O, 139 (8). (Analysts: C. J. 

Elliott, V. K. Din and A. J. Easton.) 

Greywacke, Wilton Bay, Laurie Island, BM 1972, O, 144 (8). (Analysts: C. J. Elliott, V. K. Din 

and A. J. Easton.) 

Average of 23 greywackes (Pettijohn, 1957, Table 52, analysis A). 

Greywacke-conglomerate, Scotia Bay, Laurie Island, BM 1972, O, 148 (2). (Analysts: C. J. 

Elliott, V. K. Din and A. J. Easton.) 

Subgreywacke from Tyler Slate (Precambrian) near Hurley, Wisconsin (Diller, 1898, p. 87). 

(Analyst: H. N. Stokes.) 



from the other two and corresponds to a higher sub-facies within the greenschist 
metamorphic facies. 

1972, O, 139 (1) Banded Marble. A typical mosaic-textured marble with indistinct banding. 
A few accessory minerals are present, notably muscovite, monticellite and sphene. 
1972, O, 139 (4) Garnet-hornblende gneiss. A coarse-grained gneissose rock, mainly composed of 
large garnets and olive-green hornblende. Carlsbad-twinned orthoclase and yellow biotite are 
common, and there is some quartz, epidote, abundant well-shaped sphene, apatite and iron ore. 
The garnets are richly sieved with sphene and, to a lesser extent, epidote. 



362 ROCKS FROM ANTARCTICA 

1972, O, 139 (8) Actinolite-chlorite-epidote schist. A greenschist with patchily developed layers 
of chlorite and blue-green actinolite, and finer-grained lenses of epidote, quartz and clouded 
feldspar. Some of the amphibole occurs in long, bent acicular crystals whilst the chlorite forms 
dense patches. Yellow-brown biotite is common and there is abundant well-shaped sphene. 
Locally, patches of calcite are developed and apatite is fairly common. 

1972, O, 139 (9) Garnet-hornblende schist. This compact, dark grey rock is typical of those 
from Borge Bay. The large garnets (up to 1 cm across) are set in a matrix of olive-green 
hornblende crystals in which are also crystals of oligoclase. The garnet, and to a lesser extent 
the feldspar, is sieved with sphene and epidote. There is a little quartz, calcite, biotite and 
iron ore. 

1972, O, 139 (15) Garnet-mica schist (PI. 6, 3). From the landing opposite the old wreck, this 
rock type forms the main mass of much of the island. It comprises muscovite and quartz, 
with less red-brown biotite and chlorite. There are some crystals of feldspar (mainly sodic 
plagioclase), apatite, iron ore and sparse rotated, sometimes altered garnets. In addition to 
the garnets, an augen-like texture is produced in the rock by pods or clusters of quartzo- 
feldspathic material. 

The garnet-free members of this group form the quartz-mica schists, which are also abundant 
on the island. 

Ouartz-mica schist is the common rock type from Paal Harbour (Station 1962), 
of which specimens were collected in 1937. Similar rocks were dredged in the same 
year from Station 1961, to the south of Coronation Island, together with quartzite 
and some metacalcareous rocks. 



(d) Powell and Michelsen Islands : Station 1089 

From the eastern end of Coronation Island eastwards, the Basement Complex of 
metasediments is unconformably overlain by a greywacke-shale series, which is in 
turn overlain unconformably by conglomerates (Text-fig. 4). 

On Powell and Michelsen Islands (PI. 3, 1) greywackes and conglomerates were the 
only rock types collected by Discovery II. The ship anchored in Ellefsen [Ellersen] 
Harbour, at the southern end of Powell Island, and six specimens were collected 
from the south-west corner of Powell Island, and five from Michelsen Island. The 
Biological Log notes that the smaller island is composed of low-lying rocks, rising 
at their highest to ca. 30 m. The rock, which throughout is a coarse conglomerate, 
rests at one point on a horizontal bed of greywacke, some 5 m above sea level. The 
dip of the conglomerate is south-west at an angle of 30 , the strike running NW-SE. 



(e) Fredriksen Island : Station 1090 

The ten specimens from Fredriksen Island show more variety than those from 
Station 1089. There are two conglomerates, five greywackes, one flaggy sandstone 
and two shales. The shales appear to be locally interbedded and are found infilling 
vertical cracks in the sandstone. Narrow ramifying quartz veins penetrate the rocks 
throughout. 

Rocks were collected from two localities on the west coast, from points up to 
180 m above sea level, and also from the small islet of Holmen Gras. The rocks 
dip generally southwards at angles ranging from 30 to 40 and even steeper. 



THE DISCOVERY COLLECTION 363 

(/) Laurie Island : Stations 1095 and 1959 

Ten specimens were collected from Wilton [Whitton] Bay in 1933 and four from 
Scotia Bay in 1937. They consist of greywackes, quartzites, shales and less coarse 
conglomerates but with some slate and chlorite-mica schist. It thus seems that 
dynamic or very low-grade greenschist facies metamorphism affected the sediments 
at the eastern end of the South Orkney Islands. 

Two small rocky islets in Wilton Bay were also visited in 1933. The rocks on one 
are of the usual grey type (greywacke), interbedded with a more or less vertical 
band of slate, over 1 m thick. The thin, ramifying quartz veins again cut through 
in all directions. 

Descriptions of a greywacke and a conglomerate typical of those from the east end 
of the South Orkney group are given below, together with that of the chlorite-mica 
schist from Wilton Bay, Laurie Island. Analyses of the sediments are given in 
Table VII, and the type of chlorite in the schist is discussed on p. 360. 

The composition of the greywacke (analysis 3) is close to that of an average grey- 
wacke (analysis A), except that it contains less CaO and more K 2 0, whilst the grey- 
wacke-conglomerate (analysis 4) resembles a typical subgreywacke (analysis B). 

1972, O, 144 (8) Greywacke. A typical rock of this type, with angular grains of quartz, altered 
feldspars, muscovite, chlorite and biotite, and a few grains of apatite and iron ore, in a matrix 
of fine-grained micas and clay minerals. 

1972, O, 145 (2) Greywacke-conglomerate (PI. 6, 4). A 'fine-grained' conglomerate, with well- 
rounded fragments reaching 5 mm in diameter, which consist of quartzite, rhyolite, basalt, 
variolitic basalt, andesite, silt- and fine-grained sandstone and greywacke. The latter is 
possibly of the type described above, and the matrix of the conglomerate is closely similar, 
with, in addition, abundant epidote crystals. 

1972, O, 144 (10) Chlorite-mica schist. A very low-grade schist comprising lenses of quartz and 
potassium feldspar within layers of chlorite and muscovite, with a little biotite, epidote and 
iron ore. The presence of one or two tight folds in the fabric suggests that the metamorphism 
was dynamic rather than of low-grade regional type ; the original sediment was probably a 
greywacke. 

(g) Graptolite Island : Station i960 

Four specimens were collected from Graptolite Island in 1937. Two are grey- 
wackes - the dominant rock mass - taken from 45 m above sea level. The grey- 
wackes are nearly vertical, the dip being southerly, with conglomerate (two speci- 
mens) resting unconformably on the top. 

IV. BASALTIC AND OTHER ROCKS FROM BOUVET ISLAND AND 
VARIOUS DREDGE STATIONS 

i Discovery Tablemount area 

The basalt (BM 1954, 152) forming the Discovery Tablemount, which lies some 
850 km east of Gough Island and the eastern flank of the Mid-Atlantic Ridge, was 
collected by Discovery II but had been registered previously by the British Museum 
(Natural History). It is described in detail elsewhere (Schilling & Kempe, in 
preparation) but is mentioned here since it forms part of the Discovery II collection and 
was dredged from the same station (2493) as other rocks described below (Text-fig. 1). 



364 ROCKS FROM ANTARCTICA 

The small boulder of the basalt, weighing more than 5 kg, has a pale-grey alteration 
rind, approximately 1 cm thick, mantling dark-grey fresh basalt. The alteration is 
apparent from a comparison of the chemical compositions of the inner and outer 
parts but in thin section is barely discernible. Chemically, the rock appears to be 
tholeiitic, since it contains normative quartz and hypersthene, but there is strong 
evidence, discussed below, to show that it belongs to an alkali basalt series. 

It is a porphyritic basalt (Table VIII, analysis B) with large glomerophyric pheno- 
crysts of zoned labradorite ; some augite phenocrysts occur enmeshed subophitically 
within the plagioclase, and the rock has a slight flow texture. There are small 
olivine crystals and a very occasional large phenocryst, all completely altered to 
iddingsite. Most of the rock comprises small plagioclase laths and augite grains 
in a pilotaxitic groundmass of very small labradorite crystals, augite grains and rod- 
like iron ore. Some areas of the rock are finer-grained than the rest, with glassy 
patches, and there are almost totally digested patches of a black (? cognate) xeno- 
lithic glassy basalt, which are similar to the Balleny Group basalt described below. 

Another rock from this station is a pebble (glacial erratic) of diopside-hornblende 
schist. The main constituents are olive-green hornblende and plagioclase (andesine- 
labradorite) , with some pale diopside and brown biotite. The pyroxene occurs as 
cores, largely altered to hornblende, or as new growths; the biotite is patchily 
developed. The texture is schistose and granular, with some layering : horn- 
blende only is found in some layers, whilst pyroxene is also present in others ; some 
iron ore also occurs. In origin it was probably a doleritic igneous rock, metamor- 
phosed to the amphibolite facies, but could possibly be of sedimentary derivation 
(e.g. a marl), especially since one end of the specimen shows an interlayered leuco- 
cratic band. 

Ten other erratic pebbles were dredged from the station consisting of conglomerate 
and lithified clays and marls (argillites). 

ii Bouvet Island (Bouvetoya) 

The earliest knowledge of rocks from Bouvet Island, the southernmost volcanic 
island of the Mid- Atlantic Ridge (Text-fig. 1), derived from specimens dredged some 
5 km east of the island by the Valdivia expedition and described by Reinisch (1907). 
Between 1927 and 1929 the Norvegia expeditions made the first shore collections ; 
the geology of the island was described by Holtedahl (1929) and a detailed account 
of the petrology was given by Broch (1946). 

Eighteen pebbles were dredged to the west of Bouvet Island (PI. 3, 2) in 1938 
and consist of basalts and related volcanic material, some of it deeply weathered. 
The following year a landing was made on Bouvet Island and a dozen rocks and a 
sample of beach sand collected. 

Following reports of the appearance of a new volcanic platform on the island, 
Baker & Tomblin (1964) described a visit to the island and concluded that renewed 
volcanic activity must have taken place between 1955 and 1958, during which lava 
of a trachyandesitic nature was extruded. 

Broch (1946) described rocks from Lars Island, a low islet off the south-western 
corner of Bouvet, from the sea elephant beach of the main island (opposite Lars 



THE DISCOVERY COLLECTION 



365 



Table VIII 
Analyses, some Trace Elements and CIPW Norms of Lavas 

from Bouvet Island 



sio 2 

TiO a 

A1 2 3 

Fe 2 3 

FeO 

MnO 

MgO 

CaO 

Na 2 

K 2 

H 2 0+ 

H 2 0~ 

p 2 o 5 

S 
CI 

co 2 

Less = 
Total 



Ni 

V 

Zr 

Y 

Sr 

Ba 

Rb 



q 

or 
ab 
an 

ac 

di 

hy 

mt 

hm 

il 

ap 

ct 



=S, CI 



49-3o 

3-25 
14-20 

7-97 
5-°7 
0-18 
4-00 
8-6o 
3-38 

131 
1-24 

1-02 

o-59 
0-07 

o-53 

0-03 

IOO-68 



20 
400 
250 

20 
520 
300 

nil 



6-75 

7-74 

28-60 

19-71 

12-26 
4-28 

7-5i 
2-79 

6-17 
i-39 

I-2I 



2 


A 


49-89 


49-68 


3-38 


2-28 


I4- 6 3 


18-38 


4-46 


2-70 


7-33 


6-69 


019 


0-14 


4-89 


3-97 


8-65 


10-62 


3-43 


309 


1-08 


o-86 


0-90 


0-32 


0-47 


0-52 


o-55 


o-35 


0-04 


0-02 


- 


O-IO 


0-27 


0-06 


002 


0-04 


100-14 


99-74 


Trace elements (p. 


p.m.) 


10 


- 


550 


- 


200 


- 


25 


- 


570 


— 


200 


1200 


nil 


- 


Norms 




3-7i 


1-42 


6-38 


5-08 


29-02 


2614 


21-34 


33-75 


13-08 


13-29 


10-44 


9-94 


6-47 


3-9i 


6-42 


4-33 


1-30 


o-88 


o-6i 


0-14 


Island (Station 24 


67), BM 



50-31 

2-69 

15-48 
3-67 

6-29 
0-16 

4-87 
9-06 

303 
1-40 
1-05 
1-06 
042 
0-03 

0-23 

001 

99-74 



100 
400 
250 

50 

> 1000 

600 

22 



3-98 

8-28 

25-64 

24-51 

13-04 
1024 

5-32 

5-n 
o-99 
0-52 

148 (2). 



70-47 
0-29 

12-28 
2-96 
1-99 
006 
0-18 

°-44 
4-91 

4-85 
0-50 
0-42 
0-05 
001 
0-07 
o-ii 

0-02 

99-57 



1800 



3°o 



23-06 
28-67 
36-17 

4-74 
101 

2-12 
I-92 

o-55 

0-12 
0-25 

:C. J. 



Porphyritic basalt, near Bouvet Island (Station 2467), BM 1972, O, 148 (2). (Analysts 

Elliott, V. K. Din and A. J. Easton.) 
2 Porphyritic vesicular basalt, landing place, Bouvet Island, BM 1972, O, 149 (1). (Analysts: 

C. J. Elliott, V. K. Din and A. J. Easton.) 
A Basalt, sea elephant beach, Bouvet Island (Broch, 1946, p. 24, rock no. 10). (Analyst: E. Kluver.) 
B Porphyritic basalt, Discovery Tablemount (Schilling & Kempe, in preparation). (Analysts: C. J. 

Eliott, V. K. Din and A. J. Easton.) 
C Alkali rhyolite, Lars Island, near Bouvet Island (Broch, 1946, p. 24, rock no. 4). (Analyst: E. 

Kluver.) 



366 ROCKS FROM ANTARCTICA 

Island and almost certainly the landing place for the Discovery II collection), 
from dredging south-west of the island, and from Cape Norvegia and the surrounding 
area, on the western side of the island. He divided the rocks into four groups : 
basalts, rhyolites, obsidian, and pumice and scoria. 

Three of the dredged basalts have been sectioned, as have four of the basalts 
collected from or near the landing place (? sea elephant beach) on the island. The 
remaining rocks also are either basalts or scoria. Some of the rocks closely resemble 
those described by Broch (1946), but since his material derives from a wider area, 
exact correlation is not attempted. No rhyolite, obsidian or true pumice is present 
in the Discovery II collection. It is notable that the texture of all the basalts is 
equigranular or possibly sub-trachytic, but none of them exhibits any sign of a 
poikilitic or ophitic texture. 

Brief descriptions of the sectioned rocks are given below. 

1972, O, 148 (1) Porphyritic basalt. This dredged grey rock is characterized by many large 
(ca. 8 mm) zoned labradorite phenocrysts. They are not glomerophyric, as is the Dis- 
covery Tablemount basalt (see p. 364), which this rock, although slightly coarser-grained, 
resembles. There are also a few small augite phenocrysts, contained mostly within the feld- 
spars. Small, completely altered olivine crystals and laths of plagioclase are scattered through- 
out the granular groundmass, which comprises plagioclase crystals, skeletal iron ore crystals, 
and augite and hematite grains. Glass is absent. This rock resembles Broch's (1946) specimen 
no. 10, from the sea elephant beach (Table VIII, analysis A). 

1972, O, 148 (2) A second dredged porphyritic basalt, also dark-grey, has far fewer and smaller 
reverse-zoned labradorite phenocrysts and none of pyroxene. There are traces of altered 
olivine, laths of plagioclase and granular augite in an aphanitic groundmass of pyroxene, 
equigranular ore and yellowish alteration material. The texture is sub-trachytic in its arrange- 
ment of the feldspar laths. An analysis of this rock is given in Table VIII (analysis 1) and 
discussed on page 371. 

1972, O, 148 (3) A dredged, grey, aphyric vesicular basalt. Lacking phenocrysts, this rock has 
small laths of plagioclase in an aphanitic groundmass of augite grains, granular iron ore and 
yellow alteration products. Its many round vesicles (ca. 1 mm) are filled with pinkish rhodo- 
chrosite (MnCO s ), characteristically structured with 'layering' and chevron markings picked 
out in iron staining ; the manganese presumably derives from solution in the sea water. This 
rock resembles Broch's specimen no. 2 from Lars Island. 

1972, O, 148 (4) A dredged, grey-black, fine-grained basalt, aphyric, highly aphanitic and flow- 
banded. It consists of tiny feldspar laths, pyroxene grains and abundant iron ore, with some 
calcite and yellow alteration material. 

1972, O, 149 (1) This grey-black porphyritic vesicular basalt (Table VIII, analysis 2) was col- 
lected from the cliff behind the landing place on Bouvet Island, some 10 m above sea level, 
and was considered to be the typical country rock of the island. The thin section is black and 
aphanitic to the point of glassiness, and shows flow texture. It contains a few zoned labradorite 
phenocrysts and pyroxene microphenocrysts, together with small plagioclase laths and augite 
grains, in the black groundmass, which contains many round vesicles, unfilled by secondary 
minerals. There is no trace of fresh or altered olivine. 

1972, O, 149 (2) A fragment of a red-weathering porphyritic olivine basalt from an isolated 
boulder on the landing place. There are fairly sparse phenocrysts of labradorite and some 
small crystals of olivine. The latter are sometimes fresh but often have an iddingsitized rim. 
Some are notable for their long, acicular habit. Together with laths of plagioclase and grains 
of augite, they are embedded in an aphanitic, partly glassy, iron-rich matrix. 
1972, O, 149 (4) A grey porphyritic basalt resembling the dredged sample (148 (2)), described 
above. The section shows two or three small labradorite phenocrysts, with many tiny plagio- 
clase laths, in a groundmass of even smaller feldspar, pyroxene and iron ore grains. There is a 



THE DISCOVERY COLLECTION 367 

Table IX 

Analyses, some Trace Elements and CIPW Norms of Basic Rocks 

Dredged off Dronning Maud Land 







I 




A 


2 


B 




3 


Si0 2 




4979 




46-57 


48-21 


5192 




49-08 


Ti0 2 




i-93 




i-8 5 


2-27 


0-96 




1-23 


Al 2 O a 




874 




8-20 


1335 


12-87 




18-43 


Fe 2 0. 


1 


i-33 




1-20 


4'43 


2-89 




1 90 


FeO 




ii-ii 




9-75 


8-29 


9-42 




8-51 


MnO 




0-19 




014 


0-21 


0-21 




0-22 


MgO 




15-94 




19-65 


7-35 


6-93 




5-54 


CaO 




7-80 




9-43 


1056 


io-68 




7-28 


Na 2 




1-29 




156 


2-49 


1 50 




343 


K 2 




0-64 




1-18 


0-16 


0-84 




1-20 


H 2 0+ 




1-34 




O-II 


1-30 


i-8i 




2-56 


H 2 0- 




012 




0-12 


0-41 


0-06 




002 


p»o s 




0-20 




0-26 


0-26 


009 




o-35 


S 




0-02 




- 


0-22 


- 




0-14 


co 2 




0-18 




- 


o-88 


- 




0-90 


Less O^S 


OOI 




- 


O-II 


- 




0-07 


Total 




IOO-6I 




100-02 


[00-28 


100-18 




100-72 










Trace elements (p. p.m.) 








Cr 




1800 




1250 


- 






25 


Ni 




450 




4 6 5 


70 






25 


V 




300 




100 


350 






300 


Zr 




200 




100 


150 






120 


Y 




25 




10 


40 






50 


Sr 




260 




450 


280 






370 


Ba 




300 




34° 


200 






700 


Rb 




nil 




30 

Norms 


nil 






18 


q 




- 




- 


3-32 


649 




- 


c 




- 




- 


- 


- 




1-18 


or 




378 




7-23 


o-95 


4-97 




7-09 


ab 




10-92 




II-OO 


21-07 


12-69 




29-02 


an 




16-17 




n-68 


24-78 


25-91 




28-14 


ne 




- 




1-14 


- 


- 




- 


di 




16-18 




26-84 


J6-43 


21-75 




- 


hy 




38-5I 




- 


18-58 


20-28 




20-42 


ol 




7-12 




36-11 


- 


- 




4-27 


mt 




1-93 




i-86 


6-42 


4-19 




2-78 


il 




3-67 




3-50 


4-31 


1-82 




2-34 


ap 




0-47 




0-67 


o-6i 


0-2I 




0-83 


ct 




0-41 




- 


2-00 


- 




2-05 


1 


Coarse porphyritic olivine-enstatite (picritic) basalt, 


off Dronning Maud Land 


(Station 


2605), 




BM 1972, O, : 


[50 (6). (Analyst 


s: C. J. Elliott, V. K. Din and A 


. J- Easton.) 






A 


Picrite basalt 


, mouth of Deep 


Glen, Gough Island, G 


121 (Le Maitre, 1962, Table 


10). 




2 


Ophitic dolerite or coarse 


basalt, off Dronning Maud Land (Station 2605), BM i< 


972, O, 1 


50, (3)- 




(Analysts'. C. 


J. Elliott, V. 


K. 


Din and A. J. Easton.) 








B 


Dolerite, western Dronning 


; Maud Land, 7i°i5' S, 3°oo' W (von 


Brunn, 1964, Table 1, analysis 3). 


3 


Chlorite-hornblende schist, 


off Dronning Maud Land 


(Station : 


2605), BM 1972, O, 


150 (9)- 


(Ana- 



lysts: C. J. Elliott, V. K. Din and A. J. Easton. 



368 ROCKS FROM ANTARCTICA 

trace of calcite and yellow alteration material. The rock is not dissimilar from those consid- 
ered by Broch (1946) as typical of the island - no. 1, from Lars Island, and no. 9, from sea 
elephant beach - except for the apparent absence of olivine. 

1972, O, 149 (5) Porphyritic olivine basalt. A very pale-grey rock containing sparse, slightly 
zoned phenocrysts of labradorite, fresh olivine and pyroxene. The crystals of pyroxene are 
small and, with small olivines, lie in a matrix of pyroxene and sub-trachytically arranged 
plagioclase laths. The pyroxene is patchily hematized and there is abundant skeletal iron ore. 

iii Off Dronning Maud Land 

A collection of nine basic, and fourteen acidic and metamorphic, rocks was 
dredged off Dronning Maud Land (Station 2605), some 600 km south of the Maud 
Seamount, early in 1939 (Text-fig. 1) ; they must include glacial erratics. 

The basic rocks are coarse basalts or dolerites and, in contrast to the basalts 
previously described, they are all highly ophitic or poikilitic. The six basic samples 
sectioned fall into three groups. 

Ophitic dolerite or coarse basalt (Table IX, analysis 2). This type consists largely of prisms of 
titaniferous augite ophitically penetrating labradorite laths. The remainder of the rock is made 
up of abundant skeletal iron ore and traces of brown hornblende, and chlorite and/or brown biotite. 
In at least two of the sections, the biotite appears on morphological grounds to be pseudo- 
morphing olivine. 

Coarse ophitic porphyritic basalt (PI. 7, 1). In this group, a similar mineralogy to that above 
is accompanied in one sample by abundant phenocrysts of zoned labradorite and augite. In 
the other, the phenocrysts present are of plagioclase only. Here also, biotite appears to be 
pseudomorphing olivine. 

Coarse porphyritic olivine- enstatite (picritic) basalt (Table IX, analysis 1 ; PI. 7, 2). In the 
one sectioned specimen of this type, the texture is sub-ophitic and a different mineralogy is 
found. Early formed orthopyroxene (2V ~~ 90 ) and, to a lesser degree, clinopyroxene are 
ophitic towards altered olivine, which has been totally altered to talc and skeletal and dusty 
iron ore. Labradorite, showing slight zoning ; small crystals of clinopyroxene and iron ore, 
filling in the gaps between the ferromagnesian minerals ; and a little green chlorite, are the 
other constituents of the rock. 

The acidic and metamorphic group (? erratics) consists of adamellitic and gneissose 
adamellitic rocks, quartzites, and a single chlorite-hornblende schist. Examples 
of these are described below. 

1972, O, 150 (8) Garnet-apatite gneissose adamellite. This rock has alternate coarse and fine 
layering, giving it a gneissose appearance, but is undoubtedly of igneous origin. It comprises 
mainly sericitized sodic plagioclase, quartz and microcline, with a few per cent of muscovite 
and a brown biotite, largely altered to chlorite. Accessory iron ore and zircon are present and 
there are a few small garnets. The rock is notable for its high content of apatite, both as 
aggregated patches or segregations and as large individual crystals. A similar occurrence of 
apatite was observed in a garnet gneiss from Scullin Monolith (p. 348). 

A similar mineralogy is found in the non-gneissose adamellite, 1972, O, 150 (7), which is 
moderately fine-grained : microcline, albite and quartz, accompanied by partly chloritized 
brown biotite. There is also a little muscovite, iron ore, apatite, altered allanite and zircon. 

It may be mentioned that small pebbles of aegirine granite were dredged from 
approximately 6y°^&' S, i6°oi' E and 69°i8' S, I7°09' E in 1922, by the Quest 
(Douglas, 1930, p. 152). 

1972, O, 150 (9) Chlorite-hornblende schist (Table IX, analysis 3 ; PI. 7, 3). This high green- 
schist facies ? metabasalt, resembling, although less basic, the diopside-hornblende schist 



THE DISCOVERY COLLECTION 369 

from the Discovery Tablemount area (p. 364), is comprised essentially of three minerals. Slightly 
altered andesine, olive-green hornblende and green chlorite are disposed in a compact granular 
texture, the chlorite aligned parallel to the schistosity. Small amounts of quartz, with a little 
sphene, epidote, apatite and iron ore, are also present. The type of chlorite in this rock is dis- 
cussed on p. 360), where it is compared with that from a lower grade greenschist. 

iv Balleny Islands 

A single large boulder of porphyritic olivine basalt (Table X, analysis i ; PI. 7, 4), 
weighing 37 kg, was dredged in 1938 from the area between Young and Sturge 
Islands, in the Balleny Group (Text-fig. 1 and PI. 4).* The Biological Log, reporting 
a previous passing visit (3 February 1936) when no rocks were collected, gives the 
following description of the Balleny Islands. 'None of them possesses a single peak 
but they have ice-mantled plateau-like summits, rising to some 750 m. The cliffs 
are often sheer at one end, with considerable exposures of rock, whilst the other end 
forms a gentle plateau slope dropping to 100 m or so above sea level.' 

The fine-grained glassy basalt contains numerous small phenocrysts of fresh olivine, 
and a few of plagioclase. These, together with aggregates of augite grains, are set 
in a dark slightly flow-textured pilotaxitic groundmass of magnetite octahedra, 
augite and dark glass. 

Pebbles of dolerite and 'black slaty rock' dredged near the Balleny Islands are 
amongst the first Discovery collections of 1901-4 (see p. 345). 



v Bay of Whales 

Two large boulders of greywacke, weighing 40 and 21 kg, were dredged from the 
Bay of Whales, on the edge of the Ross Ice Shelf, in 1936 (Text-fig. 1). 

Both are poorly sorted, consisting of angular quartz grains, accompanied by flakes 
of calcite and muscovite, in a heterogeneous, relatively fine-grained groundmass 
which consists of quartz, chlorite, sericite, calcite, biotite, epidote and hematite, 
with lesser amounts of tourmaline, apatite and iron ore. There is little feldspar in 
either rock. One specimen contains chlorite pseudomorphs after Phornblende and 
the groundmass is patchily developed : a single fragment of garnet-hornblende- 
quartz schist is present and the rock has a slight schistosity. The second specimen 
has hardly any orientation although the groundmass shows the same patchy develop- 
ment of, for example, green biotite and epidote. 

Geological investigations on land across the Shelf show the presence of formations 
which include greywacke, from which the present examples might derive by glacial 
action (cf. Grindley, McGregor & Walcott, 1964 ; Laird, 1964). 

vi Miscellaneous 

The Discovery II collection includes a few rocks for which, unfortunately, no 
localities are given. Noteworthy amongst these is a porphyritic olivine basalt, a 

* A trachybasalt from Buckle Island, in the Balleny Group, is included in the rock collections of the 
British Museum (Natural History) [BM 1967, P 10]. 



37° ROCKS FROM ANTARCTICA 

Table X 
Analysis, some Trace Elements and CIPW Norm of a Basalt 

DREDGED OFF THE BALLENY ISLANDS 



bl(J 2 


44"99 


47-7 


Ti0 2 


2-70 


3-2 


A1 2 3 


I5-5I 


152 


Fe 2 3 


3-43 


2-3 


FeO 


7-27 


87 


MnO 


O-IQ 


— 


MgO 


9-29 


9-7 


CaO 


9-63 


8-9 


Na 2 


4-32 


2-7 


K 2 


113 


i-6 


H 2 0+ 


0-32 


— 


H 2 0- 


O-OI 


_ 


p 2 o 5 


0-70 


- 


S 


0-05 


- 


co 2 


0-13 


- 


Less 0=S 


0-02 


— 


Total 


99-65 

Trace elements (p. p.m.) 


ioo-o 


Cr 


200 


245 


Ni 


200 


210 


V 


300 


160 


Zr 


350 


123 


Y 


50 


16 


Sr 


800 


725 


Ba 


450 


850 


Rb 


Norms 


65 


or 


6-68 


9-5 


ab 


I7-58 


22-1 


an 


19-60 


24-6 


ne 


10-28 


0-4 


di 


18-19 


15-7 


ol 


14-95 


18-3 


mt 


4-97 


3-3 


il 


5-13 


6-i 


ap 


1-65 


- 


ct 


0-30 


- 



1 Porphyritic olivine basalt, off Balleny Islands (Station 2200), BM 1972, O, 151. (Analysts: C. J. 

Elliott, V. K. Din and A. J. Easton.) 
A Average porphyritic olivine basalt, Gough Island (Le Maitre, 1962, Table 13, area 5). 

(Recalculated on an MnO-, H 2 0- and P 2 5 -free basis to 100%. ) 



very dark granular variety in which small phenocrysts of fresh olivine occur in a 
groundmass of plagioclase laths, grains of augite and iron ore. 



THE DISCOVERY COLLECTION 371 

vii Chemistry and discussion 

Analyses of basalts from or near Bouvet Island, Dronning Maud Land and the 
Balleny Islands are given in Tables VIII, IX and X, respectively. The analysis of 
the Discovery Tablemount basalt, described elsewhere (Schilling & Kempe, in 
preparation) is given as a comparison in Table VIII (analysis B). Their chemical 
characteristics are best compared by reference to the FMA and lime-alkalis triangular 
variation diagrams plotted in Text-figs. 5 and 6. In these diagrams, differentiation 
curves are plotted from earlier average analyses for the alkali basalt series of Bouvet 
Island, Tristan da Cunha and Gough Island, and also the tholeiitic basalt-andesite 
series of Deception,* and King George and Bridgeman Islands, in the South Shetlands. 

The two new analyses of Bouvet Island basalts, one dredged sample and one col- 
lected from near the landing place, fit closely with the previous analyses. These 
fall into two groups : the shore-collected basalts described by Broch (1946) and the 
earlier, dredged group reported by Reinisch (1907). In the FMA diagram the shore 
sample plots between the two earlier shore specimen analyses, whilst the dredged 
rock falls halfway towards Reinisch's three earlier analyses. Clearly the dredged 
samples are all enriched in iron and relatively highly oxidized. The remaining 
three Bouvet analyses are of late differentiate alkali rhyolite and obsidian ; there 
appear to be few or no intermediate types - trachybasalt and trachyandesite - such 
as occur on Gough Island and Tristan da Cunha, where the series end in trachytes, 
although Reinisch did report a partial analysis of an alkali trachyte. The Bouvet 
Island basalts are quartz and hypersthene normative, whereas those of Gough and 
Tristan contain normative nepheline and olivine. Le Maitre (1962), nevertheless, 
considered that the Bouvet series belongs to the alkali basalt type, and Baker 
et al. (1964), admitting that the Bouvet rocks appear tholeiitic on normative grounds, 
suggest that since they, and the similar rocks from Ascension Island, are of alkaline 
character in all other respects, they must be regarded as forming an alkali basalt 
series. For example, they fall on the edge of the alkali basalt field in the A1 2 3 - 
(Na 2 + K 2 0) plot of Kuno (i960, p. 127). Further, the mean value for Ti0 2 
(3-0) is very close to Chayes' (1965, p. 128) frequency peak for (oceanic) alkali 
basalts (2-8). The Discovery Tablemount basalt has similar alkali basalt values 
but also contains normative quartz and hypersthene and the writer suggests else- 
where that the rock may form an intermediate stage in the development of an oceanic 
tholeiite into a true island alkali basalt series. It can be seen from Text-fig. 5 
that the Discovery Tablemount basalt falls on the Tristan de Cunha differentiation 
curve and close to the Bouvet basalts, suggesting an affinity between the three types. 

The basalt dredged from between Young and Sturge Islands in the Balleny group 
is rich in fresh olivine phenocrysts. This is reflected in its chemistry (Table X), 
which is strongly nepheline and olivine normative. It is unlike any other Discovery 
basalt and has chemical affinities with the olivine basalts and ankaramites from 
Gough Island and Tristan da Cunha. Using the plot of Kuno (i960) and the Ti0 2 
content (Chayes, 1965), the rock is well within the alkali basalt field. The average 

* Recent analyses of trachyandesite bombs from Deception Island (Baker et al., 1969; Baker & 
McReath, 1971) have not been included. 



372 



Na 2 0*K 2 



ROCKS FROM ANTARCTICA 

(total) FeO 



Na,0 




MgO 



mol 



CaO 



THE DISCOVERY COLLECTION 373 

olivine basalt from Gough Island, near to which the Balleny rock plots in Text-fig. 
5, is given as a comparison (Table X, analysis A). 

The olivine-enstatite (picritic) basalt dredged from off Dronning Maud Land 
is olivine normative (Table IX, analysis 1) and resembles the picrite basalt from 
Gough Island (analysis A). The two analyses are notable for the closely similar 
content of most of their trace elements. The Discovery rock plots in Text-fig. 5 
between the Gough picrite and olivine basalts, but in Text-fig. 6 it lies, oddly, 
within the cluster of western Dronning Maud Land rocks referred to below. 

The tholeiitic ophitic dolerite or coarse basalt dredged from the same station 
(Table IX, analysis 2) plots in Text-fig. 5 within or (6) close to a group of three 
tholeiitic ophitic dolerites, and one basalt vein within them, from western Dronning 
Maud Land, described by von Brunn (1964) ; the nearest comparable analysis is 
given as analysis B, although the dredged rock is notably poorer in K 2 0- The land 
rocks form isolated groups of massifs or nunataks 10 to 30 km apart, rising 200 m 
above the surrounding snow surface, and are characterized by vertical columnar 
jointing. Von Brunn described the rocks as typical tholeiitic dolerites and the 
derivation of the dredged rocks from such a group, some 300 km to the south-west, 
is a strong possibility. Application of the chemical criteria of Kuno (i960) and 
Chayes (1965) leaves little doubt that the dolerites described by von Brunn, and the 
dredged samples, are of the circumoceanic tholeiitic type. 

Finally, the chlorite-hornblende schist (Table IX, analysis 3), although of dif- 
ferent chemical and normative composition, would plot in Text-figs. 5 and 6 close 
to the Bouvet Island basalts, whilst the greenschist from Signy Island, South 
Orkneys (Table VII, analysis 2, and p. 360), apparently derived from a basic igneous 
rock, is low in iron and consequently would plot as a magnesian tholeiite. 

V. ACKNOWLEDGEMENTS 

The author is grateful to Dr J. D. H. Wiseman for his encouragement throughout 
this work, to Mr P. M. Game for reading the section on basaltic rocks and making 
many helpful suggestions, and to Dr A. C. Bishop for critically reviewing the manu- 
script. 

Dr N. J. Snelling and Mr C. Rundle, of the Institute of Geological Sciences, 
London, are thanked for the K/Ar age determinations, and Mr B. K. Rowbury, of 
the National Institute of Oceanography, for providing the photographs of several 



Figs. 5 and 6. Triangular diagrams (molecular percentages) for analysed basaltic rocks. 5 : 
(total) FeO-MgO-(Na 2 + K 2 0). 6: CaO-Na 2 0-K 2 0. Open square, Discovery 
Tablemount basalt (Table VIII, analysis B). Solid circles, Bouvet Island basalts 
(Table VIII, analyses 1 and 2) and open circles, Bouvet Island basalts and rhyolites 
(Reinisch, 1907; Broch, 1946, p. 24). Solid triangles, basalts dredged off Dronning Maud 
Land (Table IX) and open triangles, dolerites and basalt from western Dronning Maud 
Land (von Brunn, 1964). Solid square, basalt dredged off the Balleny Islands (Table X). 
Curves are basalt series differentiation trends for Bouvet Island, B, and for other 
Atlantic islands from averages of analyses : TC, Tristan da Cunha (Baker et al., 1964, 
p. 531) ; G, Gough Island (Le Maitre, 1962, p. 1328) ; D, Deception Island and 
K.G., King George Island and Bridgeman Island, South Shetlands, both compiled by 
Tyrrell (1945, pp. 58-59)- 



374 ROCKS FROM ANTARCTICA 

Antarctic localities and for the loan of some of the Biological Logs, from the Discovery 
Collection. The Discovery photographs are copyright of the National Institute of 
Oceanography. 



VI. REFERENCES 

Angino, E. E. & Turner, M. D. 1964. Antarctic orogenic belts as delineated by absolute 

age dates. In Adie, R. J. (Editor), Antarctic Geology, Amsterdam, North-Holland : 

551-556. 
Aswathanarayana, U. 1964. Isotopic ages from the Eastern Ghats and Cuddapahs of 

India. /. geophys. Res. 69 : 3479-3486. 
Baker, P. E., Gass, I. G., Harris, P. G. & Le Maitre, R. W. 1964. The volcanological 

report of the Royal Society Expedition to Tristan da Cunha, 1962. Phil. Trans. R. Soc. 

Lond., Ser. A 256 : 439-578. 
& McReath, I. 1971. 1970 Volcanic eruption at Deception Island. Nature (Phys. 

Sci.) 231 : 5-9. 
& Tomblin, J. F. 1964. A recent volcanic eruption on Bouvetoya, south Atlantic Ocean. 

Nature 203 : 1055 -1056. 
Davies, T. G. & Roobol, M. J. 1969. Volcanic activity at Deception Island in 1967 

and 1969. Nature 224 : 553-560. 
Barth, T. F. W. & Holmsen, P. 1939. Rocks from the Antarctandes and the Southern 

Antilles. Scient. Results Norw. Antarc. Exped. ig2j-28 18 (2) : 1-64. 
Brindley, G. W. & Gillery, F. H. 1956. X-ray identification of chlorite species. Am. 

Miner. 41 : 169-186. 
Broch, O. A. 1946. Two contributions to Antarctic petrography : I. Lavas of Bouvet 

Island. Scient. Results Norw. Antarc. Exped. ig2y-28 25 (2) : 1-26. 
Burley, M. K. 1971. Joint Services Expedition, Elephant Island 1970-1971. Annex B: 

Geology Report, by Roxburgh, R. Y. & Burkitt, D. M. London : Royal Geographical 

Society : B 1-2. 
Chayes, F. 1965. Titania and alumina content of oceanic and circumoceanic basalt. 

Mineralog. Mag. 34 (Tilley vol.) : 126-131. 
Crohn, P. W. 1959. A contribution to the geology and glaciology of the western part of 

Australian Antarctic Territory. Bull. Bur. Miner. Resour. Geol. Geophys. Aust. 52 : 1-103. 
Diller, J. S. 1898. The educational series of rock specimens collected and distributed by 

the United States Geological Survey. Bull. U.S. geol. Surv. 150. 
Douglas, A. V. 1930. Deep-sea deposits and dredgings. London : Report on the Geological 

Collections made during the Voyage of the "Quest" ig2i-22, British Museum (Natural 

History) : 145-156. 
d'Urville, J. S. C. D. 1842. Voyage au Pole Sud, Histoire du Voyage, 2. Paris. 
Eskola, P. 1952. On the granulites of Lapland. Am. J. Sci. Bowen vol. : 133-171. 
Grindley, G. W., McGregor, V. R. & Walcott, R. I. 1964. Outline of the geology of the 

Nimrod-Beardmore-Axel Heiberg Glaciers region, Ross Dependency. In Adie, R. J. 

(Editor), Antarctic Geology, Amsterdam, North-Holland : 206-218. 
Groves, A. W. 1935. The charnockite series of Uganda, British East Africa. Q. J. geol. Soc. 

Lond. 91 : 150-207. 
Harrington, P. K., Barker, P. F. & Griffiths, D. H. 1972. Crustal structure of the 

South Orkney Islands area from seismic refraction and magnetic measurements. In Adie, 

R. J. (Editor) Antarctic Geology and Geophysics. Oslo, Universitets-forlaget : 27-32. 
Holland, T. H. 1900. The charnockite series, a group of archean hypersthenic rocks in 

Peninsula India. Mem. geol. Surv. Ind. 28, pt 2 : 119-249. 
Holtedahl, O. 1929. On the geology and physiography of some Antarctic and sub- 
Antarctic islands. Scient. Results Norw. Antarc. Exped. ig2j-28 3 (1) : 1-173. 



THE DISCOVERY COLLECTION 375 

Howie, R. A. 1955. The geochemistry of the charnockite series of Madras, India. Trans. 

R. Soc. Edin. 62 : 725-768. 
& Subramaniam, A. P. 1957- The paragenesis of garnet in charnockite, enderbite, and 

related granulites. Mineralog. Mag. 31 : 565-586. 
Klimov, L. V., Ravich, M. G. & Soloviev, D. S. 1964. Charnockites of east Antarctica. 

In Adie, R. J. (Editor), Antarctic Geology, Amsterdam, North-Holland : 455-462. 
Kuno, H. i960. High-alumina basalt. /. Petrology 1 : 121-145. 
Laird, M. G. 1964. Petrography of rocks from the Nimrod Glacier-Starshot Glacier region, 

Ross Dependency. In Adie, R. J. (Editor), Antarctic Geology, Amsterdam, North-Holland : 

463-472. 
Le Maitre, R. W. 1962. Petrology of volcanic rocks, Gough Island, South Atlantic. Bull. 

geol. Soc. Am. 73 : 1309- 1340. 
Marr, J. W. S. 1935. The South Orkney Islands. 'Discovery' Rep. 10 : 283-382. 
Matthews, W. R. & Maling, D. H. 1967. The geology of the South Orkney Islands. I. 

Signy Island. Scient. Rep. Falkld. Isl. Depend. Survey 25 : 1-32. 
McCarthy, W. R. & Trail, D. S. 1964. The high-grade metamorphic rocks of the Mac- 
Robertson and Kemp Land coast. In Adie, R. J. (Editor), Antarctic Geology, Amsterdam, 

North-Holland : 473-481. 
McLeod, I. R. 1964. An outline of the geology of the sector from longitude 45 to 8o° E., 

Antarctica. In Adie, R. J. (Editor), Antarctic Geology, Amsterdam, North-Holland : 

237-247. 
Miller, J. A. i960. Potassium-argon ages of some rocks from the South Atlantic. Nature 

187 : 1019-1020. 
Nockolds, S. R. 1940. Petrology of rocks from Queen Mary Land. Scient. Results Austr alas. 

Antarc. Exped. Ser. A 4 : 15-86. 
Pettijohn, F. J. 1957. Sedimentary Rocks, 2nd ed. New York, Harper. 
Pirie, J. H. H. 1905. On the graptolite-bearing rocks of the South Orkneys. Proc. R. Soc. 

Edin. 25 : 463-470. 
[1913]. Geology of the South Orkneys. [Unpublished Scottish National Antarctic 

Expedition Report.] 10 pp. 
Prior, G. T. 1907. Report on the rock-specimens collected during the 'Discovery' Antarctic 

Expedition, 1901-4. National Antarctic Expedition igoi-igo^. Natural History, 1, 

Geology, British Museum (Natural History) : 101-140. 
Ravich, M. G. & Krylov, A. J. 1964. Absolute ages of rocks from East Antarctica. In 

Adie, R. J. (Editor), Antarctic Geology, Amsterdam, North-Holland : 579-589. 
& Kuno, V. G. 1962. The charnockites of Bunger Oasis (Eastern Antarctica). Izv. 

Akad. Nauk SSSR ser. geol. iq6i, y-12 [trans.] : 57-68. 
Rayner, G. W. 1940. MacRobertson Land and Kemp Land, 1936. 'Discovery' Rep. 

19 : 165-184. 
Reinisch, R. 1907. Gesteine von der Bouvet-Insel, von Kerguelen, St. Paul und Neu- 

Amsterdam. Wiss. Ergebn. dt. Tiefsee-Exped. ' Valdivia' 10 (j) : 49-75. 
Roxburgh, R. Y. & Burkitt, D. M. See Burley, M.K. 1971. 
Sarkar, S. N., Polkanov, A. A., Gerling, E. K. & Chukrov, F. V. 1964. Geochronology 

of the Precambrians of Peninsular India : a synopsis. Sci. Cult. (Calcutta) 30 : 527-537. 
Schilling, J.-G. & Kempe, D. R. C. In preparation. The petrology of the Discovery 

Tablemount basalt. 
Smith, W. Campbell & Game, P. M. 1954. Catalogue of the Rock Collections. Part III. 

Antarctica and Australasia, British Museum (Natural History) : 165-255. 
Stinear, B. H. [1956.] Preliminary report on operations from Mawson base, Australian 

National Antarctic Research Expedition 1954-55. Rec. Bur. Mineral Resour. ig$6/44 

[unpublished]. 
Subramaniam, A. P. 1959. Charnockites of the type area near Madras - a reinterpretation. 

Am. J. Sci. 257 : 321-353- 



376 ROCKS FROM ANTARCTICA 

Thompson, J. W. 1968. The geology of the South Orkney Islands. II. The petrology of 

Signy Island. Sclent. Rep. Falkld. Isl. Depend. Survey 62 : 1-30. 
Tilley, C. E. 1930. Petrographical notes on rocks from Elephant Island, South Shetlands. 

London : Report on the Geological Collections made during the Voyage of the "Quest" ig2i-22, 

British Museum (Natural History) : 55-62. 

1935- Report on rocks from the South Orkney Islands. 'Discovery' Rep. 10 : 383-390. 

1937- Rocks from MacRobertson Land, Antarctica. Rep. B.A.N.Z. antarc. Res. Exped. 

Ser. A 2 : 17-26. 

1940. Rocks from MacRobertson Land and Kemp Land, Antarctica. 'Discovery' Rep. 

19 : 180-184. 

Tyrrell, G. W. 1945. Report on rocks from West Antarctica and the Scotia Arc. 'Dis- 
covery' Rep. 23 : 37-102. 

Von Brunn, V. 1964. Note on some basic rocks in western Dronning Maud Land. In 
Adie, R. J. (Editor), Antarctic Geology, Amsterdam, North-Holland : 415-418. 

West, S. M. 1968. Petrography of metamorphic rocks from the Inaccessible and Larsen 
Islands, South Orkney Islands. Bull. Br. Antarc. Surv. 18 : 45-57. 



D. R. C. Kempe, D. Phil. 

Department of Mineralogy 

British Museum (Natural History) 

Cromwell Road 

London SW7 5BD 



PLATE i 

Fig. i. Clarence Island Peak. 

Fig. 2. RRS Discovery II at Sandefjord Bay, Coronation Island, South Orkneys, 1937. 



Bull. Br. Mus. nat. Hist. (Miner.) 2, 7 



PLATE 1 




PLATE 2 

Fig. i. Sandefjord Bay, Coronation Island. 
Fig. 2. North coast, Coronation Island. 



Bull. Br. Mas. nat. Hist. (Miner.) 2, 7 



PLATE 2 




PLATE 3 

Fig. i. Archway formed by boulders of conglomerate, Powell Island, 1933. 
Fig. 2. Basalt, Bouvet Island. 



Bull. Br. Mus. nat. Hist. (Miner.) 2, 7 



PLATE 3 





PLATE 4 
Fig. i. The Monolith, Balleny Islands. 
Fig. 2. Young Island, Balleny Islands. 



Hull. Hi. Mas. nat. Hist. (Miner.) z, 7 



PLATE 4 




PLATE 5 

Fig. i. Photomicrograph of leucocratic granulite, Bertha Island, Sheehan Nunatak (BM 
1972, O, 129 (1)). Perthite, quartz and (diagonally from lower right) biotite and garnet. Upper 
left centre, apatite. 

Plane polarized light, x 28. 

Fig. 2. Basic (diopside) granulite, Bertha Island, Sheehan Nunatak (BM 1972, O, 129 (2)). 
Clinopyroxene, sometimes symplectically intergrown with plagioclase, (darker) hornblende 
and (paler) biotite. 

Plane polarized light, x 28. 

^ Fig. 3. Basic (pyroxene) granulite, Bertha Island, Sheehan Nunatak (BM 1972, O, 129 (5)). 
Clinopyroxene, hypersthene and (darker) hornblende. 

Plane polarized light, x 15. 

Fig. 4. Leucocratic garnet granulite, Scullin Monolith (BM 1972, O, 130 (3)). Garnet, 
perthite, quartz and a little biotite. 

Plane polarized light, x 14. 



Bull. Br. Mits. mil. Hist. (Miner.) 2, 7 



PLATE 5 




- 






PLATE 6 
Fig. i. Quartz-mica-graphite schist, Clarence Island (BM 1972, O, 133 (4)). 

Plane polarized light, x 13. 

Fig. 2. Altered quartz microdiorite, Larsen Island, off Coronation Island (BM 1972, O, 

i37(i))- 

Plane polarized light, x 16. 

Fig. 3. Garnet-mica schist, Borge Bay, Signy Island (BM 1972, O, 139 (15)). Garnet 
(lower left) with muscovite, and lesser biotite, chlorite and apatite. 

Plane polarized light, x 14. 

Fig. 4. Greywacke-conglomerate, Scotia Bay, Laurie Island (BM 1972, O, 145 (2)). Pebbles 
of quartz (top), greywacke (upper left), chert (bottom), basalt (right), and rhyolite 
(centre), in an epidote-rich matrix. 

Plane polarized light, x 12. 



Bull. Br. Mus. nat. His/. (Miner.) i, 7 



PLATE 6 




V- 4 



PLATE 7 

Fig. i. Ophitic coarse porphyritic basalt, off Dronning Maud Land (Station 2605) (BM 
1972, O, 150 (5)). 

Plane polarized light, x 31. 

Fig. 2. Coarse porphyritic olivine-enstatite (picritic) basalt, off Dronning Maud Land 
(Station 2605) (BM 1972, O, 150 (6)). Phenocrysts of enstatite, with several crystals of olivine 
altered to talc and skeletal iron ore. 

Crossed polars, x 14. 

Fig. 3. Chlorite-hornblende schist, off Dronning Maud Land (Station 2605) (BM 1972, O, 

150 (9))- 

Plane polarized light, x 15. 

Fig. 4. Porphyritic olivine basalt, off Balleny Islands (Station 2200) (BM 1972, O, 151). 
Showing large olivine phenocrysts. 

Plane polarized light, x 31. 



Bull. Br. Mus. nat. Hist. (Miner.) 2, 



PLATE 7 




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